United would have to pay over £50m for the duo as Tierney has just signed a six-year deal with the Bhoys.

Manchester United are reportedly leading the race to sign Celtic duo Moussa Dembele and Kieran Tierney, but face competition from as many as 17 other clubs.

The pair have been linked with a move to south of the border, with United, Tottenham Hotspur, Liverpool and Arsenal among the Premier League clubs keeping a close eye on both players. However, according to the Daily Record, United have stolen a march on their rivals – but could have to pay over £50m (€57.1m) to conclude both deals.

Dembele is considered one of the most promising youngsters in European football and scored 32 goals in all competitions as the Glasgow giants clinched a domestic treble last season. The France U21 international was linked with a move to Arsenal in the summer, but the Gunners did not follow up their interest with a concrete offer and the 21-year-old has remained at Celtic Park.

The Scottish Premier League champions value Dembele at £30m but believe they could get more in the current climate. With Marcus Rashford, Anthony Martial and Romelu Lukaku, United are not short of attacking options, but Jose Mourinho has made clear he wanted to add pace to his squad – and Dembele would definitely fit the bill.

Tierney, meanwhile, has allegedly been identified by the Portuguese as the man to solve his side's left-back issues. Mourinho has deployed Daley Blind and Matteo Darmian in the role this season, with Luke Shaw making only two appearances so far, both of which came as a substitute in the Carabao Cup.

Mourinho has previously expressed concerns over the 22-year-old's fitness and attitude and last week he reiterated the former Southampton man is currently his third choice at left-back. Since breaking into the first-team squad towards the end of the 2014-15 season, Tierney has established himself as a regular in Brendan Rodgers' side, playing a combined 73 games over the last two seasons.

The 20-year-old, who can also play as centre-back, is very much cut from the cloth of the modern day full-back and is a threat in the offensive third of the pitch, which has led him to provide 20 assists over the last two campaigns.

However, United could have a fight on their hands if they are to land Tierney, as the youngster signed a new deal with Celtic on Monday (30 October) that will keep him at the club until 2023.

"I've also got the right people around me to keep me grounded and it's a big credit to them. My family will be delighted and it's a big reward for them for believing in me and putting the work in all these years."

Tierney played a central role as Celtic romped to the title last season.Getty Images